1. Field of the Invention
This invention relates to measuring devices, particularly to devices that measure the diameter of circular objects, particularly those devices that measure the diameter of wheels, tires and similar vehicle support devices. More particularly, this invention relates to apparatus for the digital measurement and calibration of items. Most particularly, this invention relates to the digital measurement of diameter, circumference and the acquiring and storage of ancillary measurements.
2. State of the Art
Tire diameter is an important variable for determining the speed of an automobile. Each time a tire completes one full rotation, the vehicle it is mounted on will have gone forward (or backward) one circumference of the tire. Therefore, knowing the number of times per unit time (second or minute) the tire rotates will be directly proportional to the speed of the vehicle. But if the diameter of the tire is not correct, the speed of the vehicle will register incorrectly as well; the apparent speed will decrease as the actual size of the tire increases. The effect is especially important in automobile racing. There the exact speed is essential, moreover, the faster speed makes a small error in readout read more in absolute terms.
Conventional tire calipers measure the diameter of the tire while the vehicle is at rest. The caliper is placed over the tire and the diameter is read off a measuring device on the caliper. The optical reading of the diameter can lead to incorrect determinations of the diameter. Moreover, the markings on the caliper are difficult to read.
It would be of great benefit to have a caliper that was more easily readable and more accurately readable than the current calipers.